[Gasification] Water Treatment System for Condensates fromGasification

[Jeff Davis]

Dear Kevin and All,

Coal gasification waste, gasoline, diesel, oil, and creosote have all been 
fine dinning for our friends the microbes or the politically correct term is 
bioremediation. Sounds like composting, to me!

Jeff


On Friday 07 July 2006 10:04 am, you wrote:
> Dear Jeff, Lim, and Kusum
> ...del...
>
> > I would look into composting, as a filter and disposal system.
> >
> > Jeff
>
> The tars and acids are loosely called "creosote". Certainly, coal tar
> creosote was widely used as a wood preservative, because it prevented the
> breakdown of wood. It might be that wood creosote would tend to do the same
> thing. At any rate, it suggests that the wood creosotes would be difficult
> to compost. One thing that might be helpful is to add agricultural
> limestone to the material to be composted, to attain a neutral pH... this
> may assist with composting.
>
>
> ----- Original Message -----
> From: "Lim Mook Tzeng" <mooktzeng.lim at gmail.com>
>
> > Dear Kusum Lata,
> > The ash content in rice husk is higher than any other wood based
> > biomass...could somehow the ash influences the condensates as well,
> > causing
> > the pH to be lower?
>
> Rice ash has a very high silica content. Silica is considered to be an
> "acid" mineral as a refractory component. Is it possible that rice husk ash
> is causing the apparent pH drop?
>
> (When working with refractories, "acid" components, such as silica, will
> tend to flux "basic" components, such as CaO, MgO, K2O, and Na2O. Such
> "mineral acids" and "mineral bases" are different from conventional acids
> such as H2SO4 and HCl, or bases, such as NaOH or KOH)
>
> ----- Original Message -----
> From: "Kusum Lata" <kusumj at teri.res.in>
>
> > Possibly yes. Tom also suggested the same reason (as possible reason).
> >
> > Can it due to different kind of PAH or other organics concentration
> > levels in the condensate? Any idea.
>
> The "Wood Extractive Industries" were a significant source of acetic acid
> at one time; organic acids could indeed cause a low pH in creosotes.
> However, if rice husk ash has such an unusually high percentage of silica,
> the unusually low pH of rice husk creosote is likely related to the excess
> silica in the creosote.
>
> The mechanisms could be direct, if the silica forms a "silicic acid", to
> lower pH, OR it could indirectly lower pH by consuming KOH, or NaOH which
> are usually present in ashes, and which would otherwise tend to raise the
> pH.
>
> > On Thursday 06 July 2006 10:19 pm, Lim Mook Tzeng wrote:
> >> Dear All,
> >> On the above subject are there any available technologies to:
> >>
> >> 1)clean condensates from the gas stream to recover water and
> >> 2)dispose the contaminants (mostly are PAH compounds)
> >> 3)and to prevent contamination of environment of it.
> >>
> >> thanks
> >> Lim Mook Tzeng
>
> And to address your original question... "The best way to solve a problem
> is to eliminate it in the first place." :-) You may wish to review the
> design and operating conditions you presently employ, to reduce the
> likelihood of creosote and tar production:
> 1: Dry fuel
> 2: Uniformly sized fuel
> 3: Good air penetration to the reaction zone
> 4: Preheated air
> 5: Insulated reaction chamber to minimize heat loss.
>
> If nothing else, improvement in some or all the above areas will at least
> reduce the extent of the residual creosote problem.
>
> In a stationary filter system, tars are perhaps best captured by passing
> the tar laden gases through a bed of "small sized material". As tar is
> captured, the pressure drop increases and the bed must eventually be
> replaced. Intuitively, I would first find a way to neutralize the acids in
> the tars (such as with the addition of agricultural limestone noted above)
> and then break up the resulting material into granules that allowed air
> circulation, so that microbes would have a chance to further decompose the
> residue. A few simple experiments would quickly calibrate ones intuition
> with reality. :-)
>
> Best wishes,
>
> Kevin

-- 
Jeff Davis
Somewhere 20 miles south of Lake Erie, USA
http://www.velocity.net/~jeff0124